Methamphetamine (meth) and other stimulants are best known for their effects on the dopamine system, and hence for their propensity to be reinforcing and addictive. But meth actually increases the release and blocks the reuptake of all three monoamine neurotransmitters (norepinephrine and serotonin as well as dopamine). Meth addiction can cause alterations in brain function and cognitive performance, according to hundreds of published studies (reviewed in Barr et al., 2006; Baicy & London, 2007). The NIDA website lists a multitude of adverse effects from chronic heavy use:

However, a new review article by Hart et al. (2011)concludes that prior studies have exaggerated the harmful effects of methamphetamine on brain structure and function, cognition, mental health, and dental health. In my view, one problem with this endeavor arises in the very first sentence of the abstract:

The prevailing view is that recreational methamphetamine use causes a broad range of severe cognitive deficits, despite the fact that concerns have been raised about interpretations drawn from the published literature. This article addresses an important gap in our knowledge by providing a critical review of findings from recent research investigating the impact of recreational methamphetamine use on human cognition.

Many people can use meth recreationally, in modest doses, without becoming dependent. In fact, the review begins by noting the performance enhancing effects of meth in high-functioning, healthy adults who are occasional users. These laboratory studies are conducted in a very controlled environment, using oral administration of pharmaceutical grade methamphetamine. No one disputes that acutely administered meth can have beneficial effects on cognitive performance (Barr et al., 2006):

Numerous studies have confirmed that MA abuse is associated with cognitive impairment. Unlike the acute effects of a single low dose of MA, which can improve cognitive processing speed, attention, concentration and psychomotor performance,77,78 long-term exposure to MA may result in profound neuropsychological deficits (see Nordahl et al2).

But how does acute meth affect the performance of meth abusers? Here, the authors cite their own work on the intranasal administration of 3 doses + placebo to 11 meth abusers (Hart et al., 2008). The same computerized battery of 5 cognitive tests was given to the participants during each session. The results in their entirety:

Figure 4 shows how methamphetamine altered performance over time on selected measures.1 As can be seen, methamphetamine improved performance on both of the selected tasks. On the DAT [divided attention task, for vigilance], all active methamphetamine doses decreased the mean hit latency and increased the maximum tracking speed (P<0.05). On the DSST [digit-symbol substitution task, for visuospatial processing], only the two intermediate doses (12 and 25mg) significantly improved performance. Relative to placebo, both doses increased the total number of trial attempts and correct responses (P<0.03). No other significant performance effects were noted.

There is no explanation of why these two tasks were "selected" instead of the other three. Nor is there any indication of how this performance compares to "normative data" or to participants who are not meth abusers. This is a bit ironic, because the most annoying critique within the review is the repeated failure to accept the performance of control subjects as valid. Sure, acute meth did speed up performance on "selected" measures of "selected" tasks, but was this generally better or worse than what's observed in those without a history of long-term meth abuse?

When evaluating whether meth really isn't that bad for you, my focus is on the chronic effects of meth in long-term abusers of the drug. I'll return to this critical issue in the next post.

Footnote

1 An intriguing aspect of the data is that a massive performance drop was seen from time 0 to time 15 min in the placebo condition. One could speculate that the participants knew by then that they weren't on meth. The "Good Drug Effects" and "Stimulated" self-report ratings peaked at 15 min post-snort, so there's a disappointment-related decrement on placebo.

Sunday, November 27, 2011

"The intrinsic functional connectivity networks of human lateral frontal cortex are displayed for a 4-mm seed region that is gradually moved along the cortical surface. The functional connectivity networks are estimated on the surface using resting-state functional MRI data from 1000 young adults. The seed region begins in a region at or near the human homologue of FEF and gradually moves through distinct lateral frontal regions including those primarily coupled to limbic regions. The borders reflect estimates of networks from the 17-network parcellation of Yeo et al. (2011; see Figure 13). Note that multiple interdigitated networks converge on contiguous regions of frontal cortex. Some of these regions are embedded within sensory-motor circuits; others are absent coupling to sensory or motor regions and are embedded within networks comprising what has come to be known as the 'default network'. Thus, human lateral frontal cortex represents a nexus of multiple, interdigitated association pathways. Quantification of the distinct connectivity profiles for the lateral frontal regions (their connectivity 'fingerprints') can be found in Figure 31 of Yeo et al. (2011)."

Saturday, November 19, 2011

You've seen the short version of Resting State Network (by NeuroImage)... Are you ready for the full length version (with better sound)? Relive Cluster Analysis, Le Septième Jour and more! And prepare yourself for the riveting Dr. Kitao Sakurai, Resting-State Analyst...

Monday, November 14, 2011

Physiognomy "is the assessment of a person's character or personality from their outer appearance, especially the face." Although one might think of physiognomy as an outdated pseudoscience, along with its brethren craniometry and phrenology, facial phenotyping has undergone a resurgence of interest. Most recently, a study by Wong et al. (2011) looked at facial width and financial success in male CEOs:

But why even ask such a question? In general, the authors noted that certain psychological traits (e.g., extraversion) are associated with leadership ability, so they wondered whether an objective physical trait could predict leadership success. More specifically, they examined whether the facial width-to-height ratio (WHR) of 55 male CEOs was related to the financial performance of their companies. There's actually a sizable literature on facial WHR and aggressiveness in men:

Researchers have theorized that this relationship exists because higher facial WHRs make men seem more physically imposing, which minimizes the chance of retribution for their aggressive actions (Stirrat & Perrett, 2010).

In addition, facial WHR is a sexually dimorphic trait thought to be influenced by the effects of testosterone during adolescence. It can be objectively measured from photographs, which in this case were obtained from internet sources. The Fortune 500 firms were selected based on extensive media coverage and availability of online photos.

The 55 firms in our sample represented a range of industries, including computer manufacturing, transportation, and retail; on average, the firms had generated $38 billion in sales and had 119,684 full-time employees. The organizations in the sample included General Electric, Hewlett-Packard, and NIKE, Inc.

Results indicated that high facial WHR did indeed predict financial performance. Is this because of a more aggressive leadership style? Other studies have found a relationship between facial WHR and physical aggression (Carré & McCormick, 2008). Does this mean that successful CEOs are more likely to win bar fights (adjusted for age)? Or to spend a greater amount of time in the penalty box, so to speak?

Canadian researchers Carré and McCormick (2008) actually did find a correlation between facial WHR in hockey players and time spent in the penalty box, which was used as a proxy for physical aggressiveness. So should the most violent hockey players be the leaders of Fortune 500 companies? Perhaps, if they're companies with "cognitively simple" leadership teams,1because the facial-financial link was stronger for CEOs of such firms.

In sum, our study has advanced leadership research by showing that objective facial metrics of male leaders, as well as the broader context in which these leaders make decisions, are closely related to organizational performance. Although men with high facial WHRs may be aggressive and untrustworthy in interpersonal interactions (Carré & McCormick, 2008; Stirrat & Perrett, 2010), our research suggests that, at a societal level, organizational success may compensate for individual transgressions...

What Luscious Lips You Have

The above studies found significant physiognomic patterns in men, but these results did not hold for women. In contrast, a recent study (Brody & Costa, 2011)2claimed that a female facial feature, prominence of the upper lip tubercule, correlated with....... the ability to achieve vaginal orgasm!

Why would you ever propose such a thing? The infamous Stuart Brody has an agenda, and it's that unprotected penile-vaginal sex is the only mature and worthwhile form of sex.

A clinical observation (by the present senior author in discussion with colleagues) of an association between a novel visible marker (of likely prenatal origin) and enhanced likelihood of vaginal orgasm among coitally experienced women led to the hypothesis empirically tested in the present study. The hypothesis is that a more prominent tubercle of the upper lip is associated with vaginal orgasm (measured both as ever having had a vaginal orgasm, as well as vaginal orgasm consistency in the past month).

Now Professor Brody, what sort of "clinical observation" led you to this fanciful idea? Oh I don't know, perhaps the same one that led you to propose that you can tell by the way she walks (see Scicurious, Dr. Isis, and Jezebel). For extensive critiques of the methodology used in these studies (e.g., definitions of various sexual activities, bias, self-selection, etc.), I recommend reading Dr Petra.

There is substantial variability in the degree to which the tubercle of the lip develops. Other than its mention in the basic anatomic literature and surgical literature (especially with regard to reconstruction of labial malformation or as part of a package of aesthetic modifications to the lips), we do not know of scientific literature on aspects of the tubercle of the lip that might directly impinge upon sexual function.

OK then, the idea was pulled out of a "clinical observation" hat. Were there any other facial characteristics or bodily features that were examined but not found to correlate with penile-vaginal intercourse (PVI)?

Then we have the offensive speculation that...

...it is possible that a flatter or absent tubercle might have something in common with the at times subtle lip abnormalities associated with subtle neuropsychologic abnormalities in marginal cases of fetal alcohol syndrome...

Ladies! If you have a flat or absent tubercle, you're neuropsychologically and sexually abnormal! And how was the tubercle defined? By the participants themselves, who looked in a mirror and interpreted the verbal definitions3as they saw fit [91 of the 405 women who completed the online survey were excluded because they didn't have a mirror handy].

The Return of Physiognomy Redux

I admit that I was prepared to trash the facial width/CEO study, but upon reading it I found the following scientific merits:

hypothesis-driven

based on objective measurements, not self-report

population was not self-selected

I'm not an anthropologist or a developmental biologist and can't properly critique many aspects of that study, and I certainly won't get into evo psych here. But the contrast with the lip tubercle/vaginal orgasm paper was stark, because the latter didn't have any of the above scientific merits. Speculation about prenatal lip development is different from evidence for the effects of testosterone during adolescence.

The question on the lip tubercle was “Look closely in a mirror at the centre of your lip. Compared to the part of your top lip next to the centre, is the centre: a) prominently and sharply raised, b) prominently and gradually raised, c) slightly and sharply raised, d) slightly and gradually raised, e) flat, f) slightly lower than flat, g) no mirror available now.”

...I'm throwing knives and you don't even knowDon't you know you said you never should lieDon't you know you said you never should lieDon't you know you said you'd never surviveDon't you know you said you never should lieYou wished for what you thought would make you strongBut now that wish has left you all alone, you're on your own...

After the prolonged shower-bath, patients were typically given tartrate of antimony, which made them violently ill. Mr. Snape defended this practice however and even went on to portray himself as a persecuted man ahead of his time. But like all good skeptics, the journal editors demanded to see data documenting the effectiveness of this hideous treatment.

In the 19th century, malevolent baths were a staple in the treatment of the mentally ill (Bewley, 2008):

Baths in various forms were widely used in asylums, mainly to calm excitement. One of these was the ‘bath of surprise’, a reservoir of water into which the patient was suddenly precipitated while standing on its moveable and treacherous cover. There were also other various types of baths – the plunge bath, the shower bath and the douche (a jet or stream of water applied to some part of the body generally for medicinal purposes), all with water temperatures below 75ºF, and the hot bath, the warm bath and the tepid bath with temperatures at or above 85ºF.

Indeed, there's a lengthy history of "bathing treatments" dating back to ancient Greece and Rome (Tuke, 1858). Why was Snape any different?

The baths were administered punitively and not merely as part of standard treatment. Oh yeah, then there's the induced projectile vomiting. In his defense, Snape submitted a "selection of cases" which purportedly documented a number of successful cures, including this one:

About Me

Born in West Virginia in 1980, The Neurocritic embarked upon a roadtrip across America at the age of thirteen with his mother. She abandoned him when they reached San Francisco and The Neurocritic descended into a spiral of drug abuse and prostitution. At fifteen, The Neurocritic's psychiatrist encouraged him to start writing as a form of therapy.